Permanent magnets are made of high carbon steel and

A ferrous metal is

Which of the following is a rock?

Bessemer process is used for the manufacture of

A good building stone should not absorb water more than

Addition of pozzolana to ordinary Portland cement increases

Which of the following should be used for hearting of thicker walls?

Hydraulic lime is obtained by

The main constituent of cement which is responsible for initial setting of cement is